previously i have posted some of these tips in
this thread
- Use a tripod, your movement will make the picture come out blurry unless you can shoot at a fast enough shutter speed... and you probably can't unless you're using a flash.
- Turn off all of the lights except for the light in the tank, the other lights will just cause reflections and you won't spook the fish or attract as much interest if you're "hiding" in the dark
- Use higher speed film or bump up the ISO on your digital camera, you'll have to decide if you can live with the noise it creates, but it will help you to use a faster shutter speed. You want a fast shutter speed so your fish don't have as much time to move and blur the shot
- You can try using a larger aperture when you take the shot, shooting at f/4 will produce less depth of field than f/8 but once again it will allow you to increase your shutter speed
- Be patient, once the fish get used to your presence they shouldn't be as frightened. The others will eventually stop begging for food and getting in the way of your shot, if that's the case.
- Try try and try again. If you're using digital then take a TON of pictures, the more you take the more likely you are to have a few successful shots.
- Keep the camera parallel to the glass. If you shoot through the tank at an angle to the glass it will create some distortion. This becomes painfully evident if you ever try shooting your tank with a long macro lens. In the case of a bowfront it will be harder to get the camera parallel but just try your best, the distortion isn't as noticeable with regular/wide angle lenses
- try some tricks to get your fish to hold still, maybe you could turn out the lights for a few minutes until they stop moving... focus on the fish and turn the lights on, if they are the kind that take a minute or so to become active then you'll increase your chances of getting a shot without as much blur
- if your tank has high lighting it will make your job easier, the brighter light will allow you to use a faster shutter speed
Also keep in mind that shutter speed is not so much a function of the camera as it is a function of the lens. It is true that you can increase your shutter speed somewhat in a digital camera by increasing the ISO, but ultimately it is the maximum aperture of the lens that is the limiting factor. Most consumer level cameras do not have fixed apertures, therefor your maximum aperture will fluctuate depending on the focal length of the lens.
Look on or near the front of your lens and see if it has any numbers on it. It may look something like "7.8-23.4mm 1: 2.8-4.9" These numbers tell you first, the minimum and maximum focal length of the lens, and second the maximum possible aperture on each end of the range. Therefor if you are "zoomed out" at 7.8mm, you will be able to open the lens up to f/2.8 and achieve a faster shutter speed than you can at 23.4mm, where the maximum aperture is f/4.9. In this case the difference could mean an increase of 1-2 stops on the shutter speed.
Rules about shutter speed are generally given to reduce or eliminate the amount of vibrations/movement that a persons body/arms may introduce into the picture. If you are shooting from a tripod and the camera is static, the necessary shutter speed pretty much only increases or decreases with the speed at which the fish is moving. If the fish is swimming at even a slow speed you may have very little success if shutter speeds are below 1/60 of a second.
An additional technique that one may try, if you just can't catch the fish setting still, is to try and pan he camera along with the fish as it is moving. This may result in a more blurry background but, if done properly, can help to keep the subject more sharp.